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要旨:
Previous studies have found that visual recognition of novel 3-D objects is influenced by the degree of deviation from familiarised viewing direction. This suggests that recognition involves bringing both stimulus and representation into correspondence and this can be facilitated by knowing the observer's current viewpoint. The absence of such information in previous studies could have caused the observed view-dependence.
We addressed this issue by constructing a highly realistic virtual living room, rich in visual depth information, which served as an implicit specification of the observer's viewpoint. On a pedestal in the middle of the room, we placed various 'paper-clip' objects (Bülthoff and Edelman, 1992 Proceedings of the National Academy of Sciences of the USA 89 60 - 64). After an initial exploratory period in which subjects familiarised themselves with the room, training and recognition tests were conducted.
We compared performance in object-identification and same - different tasks (with and without the room). In the former, eight subjects learned to differentiate between objects by interactively changing their view about a fixed direction. They were then tested for generalisation to novel views. Error rates and response latencies were a function of distance from the familiar direction. The room helped reduce error rates but did not eliminate view-dependence. Results of controls in which subjects gauged their change in orientation after a deviation in viewpoint revealed similar errors as the recognition experiments; this suggests that making view deviations more explicit may reduce view-dependence even further. In the same - different tasks, five subjects had to decide whether two sequentially presented objects were the same, given an intervening shift in viewpoint. Performance was similar to the identification task. Results indicate that obversers can use implicit vantage-point information to improve object recognition performance.
